Pulsatile secretion of a hormone refers to the intermittent secretion of the hormone in a burst like or episodic manner rather than constantly, with the frequency varying from minutes to hours, determined in part by the half-life of the hormone.
T levels in a healthy male follow a diurnal variation and circadian rhythm, with levels highest early in the morning and subsequently declining as the day progresses, as a direct result of pulsatile LH secretion
A sustained steady-state level of T, however, differs from the normal circadian physiology of a healthy individual.
*If high levels of testosterone are given exogenously for extended periods of time, this can result in negative feedback to the hypothalamus and anterior pituitary, disrupting normal HPG regulation.
*As previously noted, testosterone levels in young healthy males follow a circadian rhythm. T levels are highest in the morning and lower in the evening hours. There is significant change within a 24-h period. Testosterone itself acts as a negative feedback molecule to the hypothalamus and anterior pituitary. When T levels are high enough, they signal to reduce GnRH, LH, and FSH secretion, thereby also reducing endogenous testosterone production. This occurs regardless of whether the circulating testosterone is endogenous or exogenous. If high levels of testosterone are given exogenously for extended periods of time, this can result in negative feedback to the hypothalamus and anterior pituitary, disrupting normal HPG regulation.
